The objective of this application is to solve the problem created by mycelium bacteria is provided.
The problem of swelling sludge is common to waste treatment plants in general.
The swelling sludge is formed when overgrown mycelium bacteria is caught in the flocs preventing particulate settling. The mycelium starts to form when, for example, conditions of low oxygen or low nutrients exist. Mycelium bacteria generally survives using less of oxygen and nourishment than competitors and tolerates greater variations. In this specification and claims, the term "mycelium bacteria" indicates filamentous microorganisms, which include filamentous bacteria, filamentous fungi and filamentous actinomycetes.
The chain of the events that lead to dominance by mycelium bacteria can be started if the aerator breaks down or due to loading changes in the waste treatment plant. Loading variation is caused, for example, by down-time during holidays. In addition various toxic substances disturb the operation of the waste treatment plant.
Swelling sediment problems can be prevented in advance by equipment solutions and running conditions that favour bacteria forming faster growing flocs. Once the swelling problems occur they can be resolved more easily if treatment is started early. Chemical prevention of mycelium uses oxidising chemicals or chemicals to bind mycelium.
Chemicals, such as iron and aluminium salts, used to bind and then to improve the settling of mycelium flocs are typical of those used in water treatment. Their mode of action is based on floc binding capability. In high doses they can be considered to overcome the ridgidity of mycelium bacteria and thus allow flocs to caogulate. However, polymers and floccing chemicals do not reduce the survival capability of mycelium and can effect their natural removal.
The use of chlorine in the waste treatment plants functions in the same way as peracetic acid application and effectively destroys mycelium and lowers the total number of bacteria. With a reduction in the number of living bacteria those surviving will have more access to nutrients. The use of chlorine is cheap; however, environmental considerations may make this unacceptable.
If the growth of mycelium bacteria has been due to a lack of oxygen, the easiest solution is to add a number of aerators and to check their locations. Dosing by oxygen is more effective than aeration but demands more financial investment. Oxygen gas alone will not produce a disinfective effect which is required for the removal of an advanced mycelium problem. The effectiveness and efficiency of aeration by oxygen can be improved by a molecular screen.
Ozone effectively lowers the total number of microbes in the same manner as chlorine. The benefit of using ozone is that it decays to non-toxic substances. However, ozone is too reactive and expensive with regard to equipment investment. In addition, as with chlorine gas, safety aspects have to be considered.
Ozone is more reactive than hydrogen peroxide and peracetic acid which means that it is used on non-productive side reactions when used in mycelium prevention in an activated sludge waste treatment plant.
Hydrogen peroxide is cost-effective in terms of the level of investment required. In addition it is also versatile. It can be used to form plenty of soluble oxygen and has a disinfective effect when needed. Hydrogen peroxide severs chains of mycelium bacteria, destroying their attachment points and consuming their polysaccaride protective layer. Organic iron, copper and zinc compounds catalyse this reaction. The faster growing microbes forming flocs become dominant as mycelium bacteria suffer most from the hydrogen peroxide shock dose. The fast developing catalase activity and subsequent resistance to hydrogen peroxide limits its use.